A primary limitation on the productivity of a semiconductor manufacturing facility is contamination of wafers and corresponding reductions in yield. Typically a wafer includes a number of circuits which are diced (separated) and packaged for sale; a fatal defect in one die, while not necessarily affecting the other dice, typically renders the defective die commercially worthless.
The most typical cause of defects in dice is particulate contamination of the surface of the wafer during processing. Efforts to improve yield often focus on reducing such particulate contamination.
There are several commercially available products for inspecting semiconductor wafers to identify particulate deposits. Semiconductor fabrication facilities typically use these devices to identify the number of particulate deposits on wafers, and use this information as a measure of the quality of the manufacturing process. Efforts are then made to reduce the particulate contamination in order to improve yield.